1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device and a method for fabricating the same, capable of preventing contamination of sealant and deterioration of adhesive strength caused by the spread of alignment material.
2. Discussion of the Related Art
Demands for various display devices have increased with development of information technology. Particularly, many efforts have been made to research and develop various flat display devices such as LCD, plasma display panel (PDP), electroluminescent display (ELD), and vacuum fluorescent display (VFD). Among those, the LCD device has been most widely used as a substitute for a cathode ray tube (CRT) because of thin profile, lightness in weight, and low power consumption. For example, the LCD device may be utilized as a display for a computer monitor, or a television to receive and display broadcasting signals. In order to use the LCD device in various fields as a general display, it is very important that the LCD device can display a high quality picture with high resolution and high luminance on a large-sized screen, while maintaining lightness in weight, thin profile, and low power consumption.
The LCD device includes an LCD panel displaying a picture, and a driving part supplying a driving signal to the LCD panel. The LCD panel consists of first and second substrates bonded to each other at a predetermined interval, and a liquid crystal layer formed between the first and second substrates.
The first substrate, which may be a thin film transistor (TFT) array substrate, includes a plurality of gate lines arranged along a first direction at fixed intervals, a plurality of data lines arranged along a second direction perpendicular to the first direction at fixed intervals, a plurality of pixel electrodes arranged in a matrix-type configuration within pixel regions P defined by crossing the gate and data lines, and a plurality of TFTs T enabled according to signals supplied to the gate lines for transmitting signals from the data lines to the pixel electrodes. Also, the second substrate, which may be a color filter array substrate, includes a black matrix layer that prevents light from portions of the first substrate except for the pixel regions P, an R/G/B color filter layer for displaying various colors, and a common electrode for producing the image on the color filter layer. Then, the first and second substrates are bonded to each other by sealant and maintained at a predetermined interval with spacers, and liquid crystal is injected therebetween. Meanwhile, alignment layers are formed on opposing surfaces of the first and second substrates, and rubbed to align liquid crystal molecules of the liquid crystal layer.
Next, an LCD device according to the related art will be described with reference to the accompanying drawings. FIG. 1 is a plane view illustrating an LCD device according to the related art. FIG. 2 is a cross-sectional view taken along I–I′ of FIG. 1. FIG. 3 is a plane view illustrating a first substrate of the related art LCD device to illustrate the spread of alignment material. FIG. 4 is a cross-sectional view taken along II–II′ of FIG. 3.
As shown in FIGS. 1 and 2, the related art LCD device includes first and second substrates 11a, 11b bonded to each other at a predetermined interval therebetween. The first substrate 11a is formed with a display area 21 to display a picture and a non-display area 22 of a pad region where no picture is displayed. The display area 21 is divided into an active region 21a and a liquid crystal margin region 21b. Further, the active region 21a includes a plurality of gate and data lines crossing each other, and a TFT at a crossing point of the gate and data lines. The liquid crystal margin region 21b is formed surrounding the active region 21a where the liquid crystal spreads. Even though not shown, the liquid crystal margin region 21b is hidden by a black matrix layer.
Also, as shown in FIGS. 1 and 2, a liquid crystal layer 14 and a sealant 13 are formed between the first and second substrates 11a, 11b. The sealant 13 is arranged on the boundary between the non-display area 22 and the liquid crystal margin region 21b to bond the first and second substrates 11a, 11b. 
Also, as shown in FIG. 2, first and second alignment layers 12a, 12b are formed on opposing surfaces of the first and second substrates 11a, 11b to align liquid crystal molecules of the liquid crystal layer 14 at one direction. The first and second alignment layers 12a, 12b may be formed of a polymer material such as polyamide, polyamide compound, PVA (Polyvinyl alcohol) and polyamic acid. Also, the first and second alignment layers 12a, 12b may be formed of a photosensitive material such as PVCH (PolyvinylCinnamate), PSCN (PolysiloxaneCinnamate) and CelCN (CelluloseCinnmate)-type compound. The first and second alignment layers 12a, 12b are formed before forming the sealant 13.
In order to coat the first and second alignment layers 12a, 12b on the first and second substrates 11a, 11b, an alignment layer coating device is required to uniformly coat an alignment material on the first and second substrates 11a, 11b. The alignment layer coating device may perform a coating in various methods, such as spin, spray, dip, printing, and inkjet methods. Herein, the alignment layer coating device uses the inkjet method and includes a pressure tank storing the alignment material and a raw material for the alignment layer, an alignment material provider receiving and storing an optimal amount of the alignment material from the pressure tank, and a plurality of heads discharging the alignment material to the substrate. Specifically, the alignment material is discharged to the first and second substrates 11a, 11b through the holes provided in the heads, and then the alignment material is formed into the first and second alignment layers 12a, 12b by rubbing.
Since the alignment material has viscosity low enough to pass through the holes, the alignment material spreads to all directions of the first and second substrates 11a, 11b before treatment of the alignment material discharged to the first and second substrates 11a, 11b. As show in FIGS. 3 and 4, when the alignment material (slant portion) spreads to a portion for the sealant 13 over the liquid crystal margin region 21b, the portion for the sealant 13 is contaminated by the alignment material. Also, it causes deterioration of adhesion of the sealant 13 formed on the boundary between the non-display area 22 and the liquid crystal margin region 21b to bond the first and second substrates 11a, 11b. In addition, when the first and second substrates 11a, 11b are bonded to each other, the sealant 13 is damaged due to the deterioration of the adhesion thereof.